Device for changing the direction of conveyance of flat postal items and the position of the postal items relative to their direction of conveyance

ABSTRACT

The invention relates to a device which comprises a driven carousel tray to which one or more gripper arms whose lengths can be modified in a controlled manner are fastened. At the free ends of these arms controlled joint ends having two or three degrees of freedom are provided and grippers are attached thereto. The gripper arm lengths, the spatial orientations of the grippers during rotation and the rotation speed can be controlled in such a manner that the grippers carry out linear movements along the conveyor tracks of the conveyor means to be supplied and carried away at approximately the same speed of conveyance as the respective conveyor means. During the linear movements, the joint ends and the grippers are always oriented in the same spatial orientation relative to the respective conveyor tracks.

The invention relates to a device for changing the direction ofconveyance of flat postal items and the position of the postal itemsrelative to their direction of conveyance.

As a result of their advantageous extraction position in the input unitof sorting machines the postal items are initially transported afterseparation in a longitudinal direction standing on their narrow sides.Afterwards, especially with sorting machines for large letters,periodicals etc. the postal items are turned around their longitudinalaxis into a lying position and are transported onwards lying on aconveyor belt. To eject the postal items quickly and safely into sortingcontainers when they are sorted, the direction of transport must bechanged from longitudinal to transverse since this achieves a betterejection position in the item containers. This change of transportposition in the stream of items is achieved by a change of direction ofthe speed vector by 90°. To this end in accordance with W098/49083 A2the postal items are suddenly accelerated from the conveyor belt with atransverse pusher device, which makes them leave the conveyor belt,slide onto a further conveyor belt arranged at 90° and be conveyedonwards on this belt. The impact shock on the postal items by thetransverse pusher frequently leads to the postal items being bounced orrotated or to kinking or folding of thin, delicate or partly filledpostal items In addition high material stresses as well as adifficult-to-overcome oscillation behavior of the pusher system shouldbe mentioned.

A device is known from DE 1 137 993 A in which the direction ofconveyance of the postal items and their absolute position in space, butnot however their position relative to the direction of conveyance canbe changed. In this known arrangement the postal items are gripped andreleased by the device during straight-line movement in each case bygrippers.

Furthermore the postal items have to be aligned on one edge in front ofread and print modules. This is done in inspection paths, in which, bymeans of transverse roller, as well as a speed vector in the directionof conveyance, another speed vector across the direction of conveyanceis imparted to the postal items by which they are directed onto a stopto which they align themselves. The stop is embodied as a side conveyor.Since the necessary force also has to be exercised for large and heavypostal items, the delicate postal items are frequently kinked or foldedon the stop. The postal items which are lying flat must also be divertedduring processing and moved into different conveyance levels. This isdone by means of curved belts and diverters as well as riser tracks, allof which takes up a great deal of space. In addition there is a dangerof the postal items being twisted and displaced here.

The object of the invention is to create a device for changing thedirection of conveyance of flat postal items and the position of thepostal items relative to their direction of conveyance with which stresson the postal items can largely be avoided and which requires littlespace.

In accordance with the invention the object is achieved by a device withthe features specified in claim 1. This involves one or more gripperarms with lengths that can be modified in a controllable manner beingfastened to a driven carousel tray, with controllable joint ends withtwo or three degrees of freedom, to which grippers are attached. Thelengths of the gripper arms, the spatial orientations of the grippersduring the rotation and the speed of rotation are controlled such thatthe grippers execute linear movements along the conveyor tracks of thefeeder and ejector conveyors with the approximate transport speed of therelevant conveyor. During the linear movements the joint ends with thegrippers are always in the same spatial alignment to the relevantconveyor tracks. The postal items are gripped and put. down by thegrippers.

Advantageous embodiments of the invention are presented in thesubclaims.

Thus it is advantageous to synchronize the movement of the postal itemsin the conveyors and the movement of the grippers to ensure that eachpostal item is transferred from the feed conveyor into the gripper andfrom the gripper onto the outgoing conveyor. It is also especiallyadvantageous to select the lengths, spacings and speeds of rotation ofthe gripper arms as well as the distance between the center point of thecarousel tray and the conveyor tracks such that the postal items so canpicked up or put down at the speed of conveyance with a defined spacingof the front edges or the rear edges and at a defined distance from aside reference edge of the side boundaries of the conveyor tracks.

The gripper arms can be embodied at low cost as telescopic arms.

In a favorable embodiment the grippers are embodied as clasps with atleast one movable jaw.

In order to grip or put down the postal items at different heights it isadvantageous for the gripper arms to be hinged in a controllablevertical direction.

The invention will be explained below with reference to the drawing inan exemplary embodiment.

The Figures show

FIG. 1 a schematic overhead view of a generic device for turning flatpostal items standing on their long narrow sides in the direction ofconveyance into a lying position and changing the direction ofconveyance by 90°, in which case the long sides of the items lie atright angles to the new direction of conveyance and whereby only onegripper arm is shown in different positions during a rotation;

FIG. 2 a corresponding schematic view from above, which differs from theview shown in FIG. 1 in that the direction of conveyance is changed by180° and that then the shorter sides of the items lie at right angles tothe new direction of conveyance.

As shown in FIG. 1, a continuously rotating carousel tray 1 withconstant or increasing speed, on which one or more gripper arms arelocated, is the core of the device. To make the diagram easier tounderstand, only one gripper arm 2 is shown at different points in timeduring the rotation of the carousel tray 1. The length of the gripperarm embodied as a telescopic arm can be changed in a controlled manner.In addition the gripper arms 2 can be hinged in a controlled manner in avertical direction. At the free end of the gripper arms 2 there arejoint ends 3, which can be moved in a controlled manner with two orthree degrees of freedom and which each carry a gripper 4, e.g. aclosable clasp. for picking up and putting down postal items. If thespeed of rotation is not constant it should be ensured that with unequalconveyor speeds of feed and removal conveyors postal items 5 are notaccepted and put down simultaneously.

A supply conveyor embodied as a covered belt is arranged above therotating gripper arms 2 such that it forms a tangent to the circle ofrotation of the gripper arm 2 extended to its maximum. The narrowcovered belt conveys postal items 5 standing on edge with a feed speedv_(Zu) and a constant spacing of the same edges L_(Zu), with the lowersection of the postal item protruding freely from the covered belt. Atthe point at which the front edge of a postal item or its rear edgeintersects the circle of rotation of the gripper arm 2 extended to itsmaximum length, a gripper arm 2 with an opened gripper 4, aligned to thecovered belt track must also be at the intersection point. From thispoint on the gripper arm 2 is continuously shortened at a constant speedof rotation, with the gripper 4 executing a linear movement synchronousto the movement of the postal item and the joint end 3 beingcontinuously turned in the plane of rotation, with the gripper 4 alwaysremaining aligned to the covered belt track. In this phase 1, whichlasts until the postal item 5 or the gripper 4 is at a right angle tothe gripper arm 2, the tangential speed of the gripper 4 is the same asthe feed speed v_(Zu). Since during phase 1 a synchronous sequence ofmovement between gripper 4 and postal item 5 is achieved, i.e. in nodifference speed is present, the gripper 4 can be closed around thebottom part of the postal item protruding from the covered belt and thepostal item 5 can leave the covered belts in a clasped state without anysudden force being imposed on the postal items.

After it leaves the covered belt, in phase 2 the position of a referenceedge to which the item is to be aligned to the gripper 4 is detected forexample by means of a row of light curtains and the joint end 3 ishinged 90° downwards, which transfers the postal item 5. In parallel tothis the length of the gripper arm is continuously changed to the lengthcorresponding to be defined edge spacing Lpb of the postal items 5 lyingflat, moving on a straight track at right angles to the feed directionminus the detected correction value of reference edge to the gripper 4and the joint end 3, to retain the straight alignment when the item iscarried away is continuously rotated in the plane of rotation minus adetected correction value of a possible reference edge movement togripper 4. The turning, the change of edge and the alignment is thuscompleted harmoniously (without shocks).

An conveyor for carrying away the items embodied as a flat belt, aroller conveyor or similar, is arranged offset at 90° to the feedingcovered belt below the rotating gripper arms 2 and also forms a tangentto the circle of rotation of the gripper arms 2 extended to theirmaximum length. Similarly to the postal item feed transfer, the transferof the postal items to the removal flat belt conveyor occurssynchronously in phase 3. The prespecified constant spacing of the sameedges L_(Ab) and the removal speed V_(Ab),can be determined by thegripper arm length and the transfer speed N_(Üg). In the executionsequence in accordance with FIG. 2 the direction of conveyance ischanged by 180°, with the postal items 5 also being moved from thestanding position into a lying position with edge alignment. Phase 1thus executes as shown an FIG. 1, but in phase 2 the joint end 3 is notcontinuously rotated in the plane of rotation but only by the detectedcorrection value of reference edge movement to gripper 4, and in phase 3one or more outgoing belts can be arranged at different levels, in whichcase the gripper arms 2 can be hinged in a controlled manner in avertical direction in a similar way to what are known as octopus ridesin amusement parks, to implement the transfer to different levels.

1. A device for changing a direction of conveyance of flat postal itemsand a position of the postal items relative to their direction ofconveyance, comprising: a feed conveyor arranged to fed the postal itemson a conveyor track with a speed of conveyance v_(Zu) such that thepostal items are carried away from the device by a conveyor on a secondconveyor track with a changed direction of conveyance and a speed ofconveyance V_(Ab), a driven carousel tray arranged to be fastened withone or more gripper arms with lengths which can be modified in acontrolled manner, controlled joint ends having two or three degrees offreedom and arranged at free ends of the gripper arms to which grippersare attached, wherein the speed of rotation of the carousel tray andduring the rotation of the carousel tray the lengths of the gripper armsas well as the spatial orientation of the grippers are arranged to becontrolled in such a way that the grippers execute linear movementsalong the first conveyor track with approximately the speed v_(Zu) andalong the second conveyor track with approximately the speed v_(Ab),wherein during the linear movements the spatial orientation of the jointends remain the same as the orientation of the grippers to the relevanttransport track, and wherein the postal items are gripped and put downby the grippers during their linear movements.
 2. The device accordingto claim 1, wherein the movement of the postal items in the conveyorsand the movement of the gripper arms and gripper are synchronized toensure that each postal item is transferred from the feed conveyor intothe gripper and from to gripper onto the outgoing conveyor.
 3. Thedevice according to claim 1, wherein the lengths, spacings and speeds ofrotation of the gripper arms, as well as the spacing of the center pointof the carousel tray from the conveyors, are selected so that the mailitems can be picked up or put down at the conveyor speed in a definedspacing of the front edges or the rear edges and in a defined spacingfrom a side reference edge of the side boundaries of the conveyortracks.
 4. The device according to claim 1, wherein the gripper arms aretelescopic arms.
 5. The device according to claim 1, wherein thegrippers comprise clasps with at least one movable jaw.
 6. The deviceaccording to claim 1, wherein the gripper arms are hinged in a verticaldirection in a controlled manner.